Biodiversity Values of Geographically Isolated Wetlands In the United States

METHODS

OBJECTIVES

Kathleen Goodin & Pat Comer

CONTEXT

Develop a nationally standardized classification of geographically isolated wetlands Identify rare & vulnerable species & communities that are supported by or restricted to these wetland types Evaluate Knowledge Gaps Inform decision makers and land managers at federal, state and local levels.

Solid Waste Agency of Northern Cook County vs. U.S. Army Corps of Engineers (2001)•The Court ruled that the Clean Water Act may not have jurisdiction over some isolated wetlands and other waters.

• Update National Ecological System Classification • Develop a working Definition of “Isolated”• Link at-risk species and communities to isolated wetland systems using expert knowledge• Evaluate knowledge gaps

Obligate Facultative Unknown Total

Animals 18 (8) 12 (5) 3 33 (13)

Plants 77 (37) 141(36) 23 241 (73)

Total Species 95 (45) 153 (41) 26 274 (86)

Associations 176 103 0 279

At Risk Elements (ranked G1-G3) Tied to Isolated Wetlands (numbers in parentheses are listed under the Endangered Species Act)

RESULTS• There are 276 wetland Ecological System types currently identified in the United States. Eighty one of these (29%) meet our working definition of “isolated” and may no longer be protected under the Clean Water Act as after SWANCC.

• A total of 274 at-risk species are supported by isolated wetlands, with more than one-third (35%) apparently restricted to these wetland types.

• A total of 86 plant and animal species listed as threatened, endangered, or candidates under the Endangered Species Act are supported by isolated wetland habitats. This represents about 5% of all plant and animal species currently listed under the Act. A majority (52%) of these listed species are completely dependent on isolated wetland habitat for their survival.

•Nearly half of isolated wetland system types are known to support at least one listed species under the Endangered Species Act.

•Nearly one-quarter of U.S. counties (725 counties, or 23%) harbor at least one at-risk species associated with isolated wetland habitats, and 80 of these counties have five or more such species.

Acknowledgements We wish to express our sincere appreciation to biologists and ecologists from the natural heritage programs that contributed expertise, review and data. The extensive field experience represented by this network of scientists and their close working partners form the basis for this analysis. We are grateful for the financial assistance provided by the U.S. Environmental Protection Agency (EPA), Office of Wetlands, Oceans and Watershed — Wetlands Division through a Wetlands Program Development Grant.

North Pacific Montane Wet Meadow Pat Photo © Comer

Data Available at www.natureserve.org/explorer

Working Definition of Isolated (For purposes of study)

Isolated wetland ecological system types are natural wetlands where >80% of all known occurrences are completely surrounded by uplands and there are no apparent surrounded by uplands and there are no apparent surface water inlets or outlets.

Houston Toad (Bufo houstonensis). Photo © Dr. Robert Thoman

Prairie White Fringed Orchid (Platanthera leucophaea) Photo © Jim Henderson

Northern Columbia Plateau Basalt Pothole Pond, Washington Photo © Rex Crawford

Virginia Sneezeweed (Helenium virginicum). Photo © Al Schotz

Southern Piedmont / Ridge and Valley Upland Depression Swamp

 

This system represents isolated wetlands primarily of the Piedmont in small, shallow basins in upland settings where water pools due to limited soil drainage. Also for now are related wetlands of the adjacent Ridge and Valley and Southern Blue Ridge (both extremely rare and small-patch examples). Most known examples occur on mafic rocks. The typical hydrology is seasonally flooded. Most examples consist of forests of wetland oaks, but a few are treeless or open-canopied ponds. Vegetation is zoned with an outer ring of trees, a more interior ring of shrubs, herbs and vines, and a central area with or without standing water year round depending on precipitation. A few examples occur in the adjacent Southern Blue Ridge and Ridge and Valley ecoregions. This system also includes the wet hardwood forests ("Iredell Flatwoods" or "Gabbro Glades") which occur on gently sloping terrain or shallowly depressed upland flats over gabbro-derived clays in the Piedmont of Georgia and South Carolina.    AL, GA, NC, SC, VA

    Assoc. Quercus palustris - Quercus bicolor / Carex spp. Forest G1G3 VA:S2

     

Quercus phellos / Carex (albolutescens, intumescens, joorii) - Chasmanthium laxum / Sphagnum lescurii Forest

G2G3 VA:S2?

     Scirpus cyperinus - Dulichium arundinaceum / Sphagnum spp. Herbaceous Vegetation G1Q VA?

   

Plants Boltonia sp. 1 G2? NJ:SNR, VA:S1

     

Carex decomposita (Cypress-knee Sedge) G3 DC:SH, DE:S1, MD:S1, VA:S2

      Isoetes piedmontana (Piedmont Quillwort) G3 VA:S1?

     Isoetes virginica (Virginia Quillwort) G1 NC:S1, VA:S1?

This system of ponds and wetlands is found in the Interior Highlands of the Ozark, Ouachita, and Interior Low Plateau regions, ranging north from the southern and central Appalachians to the Northern Piedmont regions. Stands occur in basins of sinkholes or other isolated depressions on uplands. Soils are very poorly drained, and surface water may be present for extended periods of time, rarely becoming dry. Water depth may vary greatly on a seasonal basis, and may be a meter deep or more in the winter. Some examples become dry in the summer. Soils may be deep (100 cm or more), consisting of peat or muck, with parent material of peat, muck or alluvium. Ponds vary from open water to herb-, shrub-, or tree-dominated systems. Tree-dominated examples typically contain Quercus species, Platanus occidentalis, Fraxinus pennsylvanica, Acer saccharinum or Nyssa species, or a combination of these. In addition, Liquidambar styraciflua may be present in southern examples. Cephalanthus occidentalis is a typical shrub component. The herbaceous layer is widely variable depending on geography.

AL, AR, DE, GA, IL, IN, KY, MD, MO, NC, NJ, OH, PA, TN, VA, WV

  Assoc. Carex aquatilis - Dulichium arundinaceum Herbaceous Vegetation G1? VA:S1

    Carex barrattii Herbaceous Vegetation G1 VA:S1

    Cephalanthus occidentalis / Dulichium arundinaceum Shrubland G1 VA:S1

    Cephalanthus occidentalis / Torreyochloa pallida Shrubland G1? VA

   Orontium aquaticum - Schoenoplectus subterminalis - Eriocaulon aquaticum Herbaceous Vegetation

G1 DE, VA:S1

   

Quercus palustris / Panicum rigidulum var. rigidulum - Panicum verrucosum - Eleocharis acicularis Herbaceous Vegetation

G1 VA:S1

 

  Platanus occidentalis - Fraxinus pennsylvanica - Ulmus americana / Cornus sericea Forest

G2G3 MD?, NJ:S1S2, PA?

    Scirpus cyperinus - Dulichium arundinaceum / Sphagnum spp. Herbaceous Vegetation G1Q VA?

    Sparganium americanum - Epilobium leptophyllum Herbaceous Vegetation G2G3 VA:S1?, WV

    Vaccinium macrocarpon / Pogonia ophioglossoides Dwarf-shrubland G1Q VA

  Plants Boltonia sp. 1 G2? NJ:SNR, VA:S1

   Carex decomposita (Cypress-knee Sedge) G3 DC:SH, DE:S1, MD:S1,

VA:S2,

    Fimbristylis perpusilla (Harper's Fimbristylis) G2 DE:S1, MD:S2, VA:S1

    Helenium virginicum (Virginia Sneezeweed) G2 (LT) VA:S2

    Isoetes virginica (Virginia Quillwort) G1 VA:S1?

    Muhlenbergia torreyana (Torrey's Dropseed) G3 MD:S1, NJ:S3

    Platanthera leucophaea (Eastern Prairie White-fringed Orchid) G3 (LT) VA:S

   

Scirpus ancistrochaetus (Northeastern Bulrush) G3 (LE) MD:S1, PA:S3, VA:S2, WV:S1

These Sphagnum and shrub peatlands occur in basins south of the Laurentian-Acadian region down to near the glacial boundary in the northeastern and north-central U.S. They are found in colder regions of the division, mostly in areas where glacial stagnation left coarse deposits and glacial depressions (many are "kettleholes"). The basins are generally closed, i.e., without inlets or outlets of surface water. The nutrient-poor substrate and the reduced throughflow of water create oligotrophic conditions fostering the development of Sphagnum peat and the growth of peatland vegetation. In deeper basins, the vascular vegetation grows on a Sphagnum mat over water, with no mineral soil development. Ericaceous shrubs and dwarf-shrubs (e.g., Chamaedaphne calyculata) dominate, with patches of graminoid dominance. Some peatlands may have a sparse tree layer. Although these are often called bogs, in most cases they are technically fens (albeit nutrient-poor ones), as the vegetation remains in contact with the groundwater.  

CT, IL, IN, MA, ME, MI, MN, NH, NJ, NY, OH, ON, PA, RI, VT, WI

 Assoc. Myrica gale - Dasiphora fruticosa ssp. floribunda / Carex lasiocarpa - Cladium

mariscoides Shrub Herbaceous VegetationG2G3 NJ:S1, PA

  Animal Caenestheriella gynecia (Feminine Clam Shrimp) G2G3 PA:SNR

North-Central Interior and Appalachian Acid Peatland

North Central Appalachian Seepage Fen

This system is found in scattered locations in the central Appalachians and eastern Great Lakes regions. Mostly non-forested, these open fens develop on shallow to deep peat over a sloping substrate, where seepage waters provide nutrients. Conditions are often circumneutral to alkaline. Sedges are the major dominants. Packera aurea, Symplocarpus foetidus, and Lobelia kalmii are among the characteristic forbs. Some of these areas are kept open by grazing, and succession to shrublands may occur in the absence of disturbance.   

CT, MA, MD, NJ, NY, PA, VA, VT, WV?

 

Assoc. Alnus serrulata - Lindera benzoin / Osmunda regalis var. spectabilis - Carex tetanica Shrubland

G1? VA:S1

   Carex atlantica - Solidago patula var. patula - Lilium grayi / Sphagnum bartlettianum Herbaceous Vegetation

G1 NC, TN?, VA?

 

  Cornus amomum - Salix candida / Dasiphora fruticosa ssp. floribunda / Carex stricta Shrubland

G3? CT, MA, NJ:S2S3, NY, OH, PA

   

Juniperus virginiana / Dasiphora fruticosa ssp. floribunda / Carex flava - Carex tetanica Shrub Herbaceous Vegetation

G1G2 NJ:S1S2, NY, PA

   Morella pensylvanica - Dasiphora fruticosa ssp. floribunda / Carex sterilis - Carex flava Shrub Herbaceous Vegetation

G2 NJ:S2, NY?, PA

 

Plants Carex sp. 2 (Fen Sedge) G1 NC:S1, VA:S1, TV:SNR

   

Chelone cuthbertii (Cuthbert's Turtlehead) G3 GA:S1, NC:S3?, SC:SNR, VA:S2, TV:SNR

This system consists of seepage-fed wetlands in the southern Appalachians on gentle slopes, with substantial seepage flow. Vegetation is variable, both within and among examples, but lacks vegetation characteristic of bogs or floodplains. This is a small-patch system occurring over a wide elevational range, nearly to the highest peaks, but is generally lacking from flat valley bottoms.  

AL?, GA, KY?, NC, SC, TN, VA, WV?

 

Assoc. Carex gynandra - Platanthera clavellata - Drosera rotundifolia - Carex ruthii - Carex atlantica / Sphagnum spp. Herbaceous Vegetation

G2 NC, TN, VA?

   Diphylleia cymosa - Saxifraga micranthidifolia - Laportea canadensis Herbaceous Vegetation

G3 GA, NC, SC?, TN, VA

   

Impatiens (capensis, pallida) - Monarda didyma - Rudbeckia laciniata var. humilis Herbaceous Vegetation

G3 GA, NC, SC, TN, VA, WV?

   Schoenoplectus robustus - Juncus gerardii - Hordeum jubatum - Atriplex patula Herbaceous Vegetation

G1 VA

 

Plants Cardamine clematitis (Mountain Bitter Cress) G2G3 AL:SH, NC:S2, SC:SNR, TN:S2, VA:S1S2, TV:SNR, GS:P2

   

Chelone cuthbertii (Cuthbert's Turtlehead) G3 GA:S1, NC:S3?, SC:SNR, VA:S2, TV:SNR

   

Saxifraga caroliniana (Carolina Saxifrage) G2 GA:SH, NC:S2, TN:S1S2, VA:S2?, WV:S1, TV:SNR, GS:PNR

Southern Appalachian Seepage Wetland

Isolated Wetlands and At-Risk Species of the Mid-Atlantic

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By Kathleen Goodin, Pat Comer & Denny Grossman